Climate Change Module

What controls Earth’s temperature?

  • Amount of energy received by the sun
  • Reflection vs absorption of sun’s energy (albedo)
  • The amount of energy retained by the earth’s atmosphere.

Amount of energy received by the sun

  • The path of the earth around the sun and the earth’s angle vary at different time scales.
  • Has been an important influence for glacial periods (every 100,000 years) over the past 500,000 years.
  • Milankovitch Cycles

image different components of Milankovitch Cycles

Amount of energy received from the sun?

  • Sunspots – reflect the magnetic activity of the sun and the sun’s brightness.
  • Approximately an 11-year cycle

graph of 11-year solar cycles

Amount of energy reflected to space

  • Albedo (reflectivity)
  • Lighter things reflect more light energy
  • Darker things absorb more light energy (heat)
  • Creates positive feedback
  • Aerosols lead to increased reflection of solar radiation (Volcanic activity -> cooling).

diagram of earth's albedo

Amount of energy retained by the atmosphere

  • The greenhouse effect: Energy is retained.
  • Gases in the atmosphere trap heat (CO2, CH4, NOxs, CFCs)

diagram of greenhouse gas influence on earth's energy

Global energy balance

diagram of global energy balance

What is “global temperature”?

Global surface temperature is calculated by averaging the temperatures over sea and land. Communicated as an anomaly.

global map of surface temperature

What is “global temperature”?

  • Many groups across the world have generated datasets of global temperature
  • One example: Hansen et al. 2010 from Goddard Institute for Space Studies, NASA http://pubs.giss.nasa.gov/docs/2010/2010_Hansen_etal_1.pdf
  • Different datasets from weather stations all over the world were compiled.
  • Used a model to interpolate (smooth) data for land
  • Use bucket (ships) and satellite measurements calibrated with ship measurements for the ocean

What would cause global temperature to change?

How do we measure atmospheric CO2?

  • Dr. Dave Keeling started measuring the CO2 concentration in air in 1958
  • Collected air in vacuum-cleared glass flasks and measured CO2 content
  • Still measured with the method today (as well as sensors)

map of Mauna Loa

How do current changes compare to past climate?

  • The earth is 4.54 billion years old
  • The last ice age was 110,000 to 12,000 years ago, with peak glaciation 22,000 years ago
  • The world looked different!
    • Northern USA and Canada covered by ice (grey)
    • Southern US covered by taiga (coniferous forest) and grassland
    • Southern Europe was tundra

Ice cores!

picture of ice core

Ice cores!

picture of ice core in storage

Ice cores!

picture of bubbles in ice core

Key questions in module

  • What is the evidence for a changing climate?
  • How do find & interpret data sources behind leading climate change indicators?
  • How do we read and plot this data in a scriptable & reproducible manner?
  • How do we communicate technical analysis in notebook formats that combine code, text, and visuals?

Key Data Science Objectives

  • Reading data with diverse and unexpected formats
  • Searching for how to solve problems
  • Question 10 has more independence when addressing a question with data.